The paramyxoviruses, respiratory syncytial virus (RSV) and parainfluenza virus are the chief respiratory pathogens of human infancy. A specific, quick, easy and economical diagnostic test would greatly aid the clinician in diagnosis and treatment of paramyxovirus infections. The aim of this proposal is to develop a direct non-radioactive DNA:RNA hybridization test to diagnose paramyxovirus infections. Phase I development will be performed using RSV detection in human Hep-2 cell cultures as a model system. Detection of viral RNA will be based on in situ hybridization of non-radioactive biotinylated RSV specific DNA probes. Visualization will involve detection of biotin, based on enzymatic and flurorescent methods. This model will allow for the optimization of sample treatment and hybridization/detection conditions in order to attain an easy, reliable, sensitive and economical diagnostic assay for RSV infection. After feasibility is established, in Phase II, this protocol will be applied to detect other paramyxovirus infections using the appropriate biotinylated DNA probes. The major emphasis of Phase II will be directed towards establishment of this procedure for differential paramyxovirus detection in the clinical laboratory.